Continued from anther thread that wandered off to battery subjects...
I often hear people saying they replace a motorbike battery every season. Why should this be so, when the battery in a car can last five years?
Possible causes: oil tank heat; vibration; wonky voltage regulators. Others?

My setup:
A "gel" cell, 5 to 7 AH. Gels don't put out lots of amps, but I don't need to crank a starter. I jam slices of closed-cell foam between the battery and the sides of the oil tank to cushion vibrations and insulate the battery from heat. I use an electronic voltage regulator from a car, since it cost me less than a Harley aftermarket regulator would have. Also, car voltage regulators are produced by the millions and have had the kinks ironed out of them; they are reliable. Bike voltage regulators are not only more expensive but are more likely to fail, in my experience.
I put a link to a picture of my regulator in the projects forum. It's kind of ugly, so I've been looking at other regulators that might work (1971 Dodge Dart ~$10 plus $4 for a heavy duty diode).
I can post wiring diagrams.
I also use a very simple trick to drop about 0.7 volts off of the regulation 14.5 volts (approx) the typical car regulator sets since 14.5 volts is too high for a small, hot gel cell or even a wet one of that size.

I think one reason that car batteries outlast bike batteries is that cars tend to be used on a more regular basis, so the batteries are constantly being worked and charged. Pan batteries lead a hard life anyway, as they are surrounded by a hot oil tank. (unless they are a police model, like mine.). If your bike sits idle for long periods, use one of the modern trickle chargers to keep the battery charged and check the electrolyte level regularly. If you live in the frozen north and lay your bike up over winter, take the battery out and store it somewhere warm and well ventilated and charge it once a month. The worst bike I've had for eating batteries was my Dyna Glide. I guess any electric start Harley is going to give a battery a hard time.

Gotta agree about the Hot oil around the battery.
Tough conditions for the battery.
I mentioned this in the other sidetracked post on batteries. About the XJ-6 battery additive. From JC Whitney. I think that's the name of that stuff..
Now I'm not trying to push any snake oil. But the battery I had in my 'ol '97 Road King is original & has been in service & still is. The last 4 years in my tractor. I did add that additive, when it was 2 yrs.old
Now my "Parts Chaser 2" Servi uses a auto battery. & it lasts & lasts.
I used to be a big believer in 1 year =1 battery.
Know a guy with a [goldwing] & he's getting close to 5 years on a battery. There is no reason to not get more life out of a battery. I do use a battery tender. Only here & there.